Develop a radioimmune assay to detect cell membrane bound feline oncorna virus-associate membrane antigen (FOCMA) in preleukemic cells. Seek correlations between appearance of FOCMA and preleukemic events associated with feline leukemic virus (FeLV) oncogenesis, including gas induction, productive FeLV infection, lymphopenia, thymic atrophy, suppression of T cell function, and FOCMA antibody production. Determine sites of preneoplastic cell development in vivo. Measure FOCMA shedding into body fluids and also the time course of release correlated with the course of disease. Compare quantitatively the FOCMA expression on preleukemic and leukemic tumor cells.